Location: Various

Details:
Any day, if you lhave certain people registered in your phone on the PokéGear, you will learn of a Pokémon swarm somewhere in Johto. These Pokémon are usually incredibly rare or non-existant within the locales so this is a perfect way to obtain them. The Pokémon are as follows:

Location: Various

Details:
Reid does a daily radio lottery at the Goldenrod Radio Tower. By tuning into the Lucky Number Show, you'll find out what those numbers are. This lottery provides 5 numbers and you need to have any of your Pokémon's IDs match up to the numbers in order to win. The more numbers matched, the better the prize. The top prize is a Master Ball, so play often.

Location: Goldenrod Underground

Details:
The Goldenrod Underground is a unique shopping mall underneath the main city. Many rare and exotic items can be bought here, and services are available you can't find in a normal Pokemart. They are as follows:

Location: National Park
Days: Tuesday, Thursday, Saturday

Details:
On Tuesdays, Thursdays and Saturdays, the National Park hosts the Bug Catching Contest. In the contest, you'll be given a set of Park Balls and the chance to catch rare Bug-type Pokemon for a shot at the grand prize. For more details, click here.

Location: Olivine City
Days:
Wednesday/Sunday (Vermillion to Olivine)
Monday/Friday (Olivine to Vermillion)

Details:
Once you have the S.S. Ticket and have already been to Kanto, you'll be able to make return trips between Johto & Kanto twice a week from each port. The trip to Kanto and the trip to Johto both have a different batch of trainers on board.

Location: Indigo Plateau
Days:
Monday & Wednesday

Details:
Every Monday and Wednesday after you've defeated the Elite Four, your Rival appears at the Indigo Plateau to have a rematch. It's good training.

Rival	Sneasel	Crobat	Magneton	Gengar	Alakazam	Meganium
Battle Type Single Battle Items	Level 48	Level 45	Level 48	Level 46	Level 46	Level 50
	Attacks: Quick Attack Screech Faint Attack Fury Cutter	Attacks: Toxic Bite Confuse Ray Wing Attack	Attacks: Thunder SonicBoom Thunder Wave Swift	Attacks: Mean Look Curse Shadow Ball Confuse Ray	Attacks: Recover Future Sight Psychic Reflect	Attacks: Giga Drain Body Slam Light Screen Safeguard
Totodile Chosen

Rival	Sneasel	Crobat	Magneton	Gengar	Alakazam	Typhlosion
Battle Type Single Battle Items	Level 48	Level 45	Level 48	Level 46	Level 46	Level 50
	Attacks: Quick Attack Screech Faint Attack Fury Cutter	Attacks: Toxic Bite Confuse Ray Wing Attack	Attacks: Thunder SonicBoom Thunder Wave Swift	Attacks: Mean Look Curse Shadow Ball Confuse Ray	Attacks: Recover Future Sight Psychic Reflect	Attacks: Smokescreen Quick Attack Flame Wheel Swift
Chikorita Chosen

Rival	Sneasel	Crobat	Magneton	Gengar	Alakazam	Feraligatr
Battle Type Single Battle Items	Level 48	Level 45	Level 48	Level 46	Level 46	Level 50
	Attacks: Quick Attack Screech Faint Attack Fury Cutter	Attacks: Toxic Bite Confuse Ray Wing Attack	Attacks: Thunder SonicBoom Thunder Wave Swift	Attacks: Mean Look Curse Shadow Ball Confuse Ray	Attacks: Recover Future Sight Psychic Reflect	Attacks: Surf Rain Dance Slash Screech
Cyndaquil Chosen

Location: Union Cave
Days: Friday

Details:
Every Friday, you'll be able to find Lapras swimming in the Union Cave's basement. Even if you catch it the previous week, another will appear the Friday afterwards. You need Surf to reach the Lapras so you can't get it until after you beat Morty.

Lapras Level 20

OT: Yours ID: Yours Hold Item: None

Growl Slam Mist Body Slam

Location: Mt. Moon
Days: Monday

Details:
Every Monday night at Mt. Moon's summit you'll find a group of Clefairy dancing in the moonlight. After observing the dance for a while, they'll spot you and flee. Smash the rock they're parading around to get a Moon Stone.

Location: Various
Days: Every Day

Details:
These siblings appear once a week in special locations, waiting to give you a unique attack boosting item. Their names are all fairly obvious puns. Make sure to meet them all to boost your Pokemon's moves!